Why the Curtain Has Not Fallen on OPERA

For those of you who read the news reports about OPERA, and its potentially (not) superluminal neutrinos, on Thursday or on Friday morning, and stopped following after that, I have news for you: almost everything that appeared in the press up to that point was wrong in some important details.  Thanks to my readers and their comments and detective work, we’ve collectively managed to figure out much more clearly what’s actually going on.  I put up a relevant post Thursday morning and another Thursday afternoon, but I especially recommend Friday morning’s post (and comments) and Friday afternoon’s post (and comments).  I really emphasize the value of the comments; I have some very well-informed and insightful readers who contributed a great deal.  You can read this summary post first, and then go back to the older posts and read through the earlier viewpoints and the detailed commentary.  [The science press has caught up, though; here’s an accurate article from 2/27 in Nature.]

Most press reports on Wednesday, Thursday and Friday boiled down to this statement: “The OPERA folks found a loose wire, and when they fixed it their timing shifted by 60 nanoseconds [billionths of a second], bringing neutrino speeds right back to where they were supposed to be.”  That’s certainly what the original Science Insider article implied, from which many articles took their cue.  This is illustrated in the Figure below (labeled (b) to be consistent with a figure from an earlier post. )  The original OPERA result — that neutrinos arrived 60 nanoseconds before they were expected to — is shown as (a).

But this statement is completely wrong.

(a) OPERA originally claimed neutrinos arrived early by 60 nanoseconds (ns), with an uncertainty of about 10 nanoseconds, shown by the black vertical bar. (b) Incorrect press reports widely suggested that OPERA had found a mistake (a "loose wire") that caused a 60 nanosecond shift and brought the measurement back into agreement with expectations. (d/e) But in fact the two problems identified so far by OPERA, a sensitivity to an optical fiber's exact orientation and a miscalibrated timing oscillator, are both large compared to the original measurement, are both imprecisely known, and point in opposite directions. This makes the situation entirely unclear for the moment.

In fact the OPERA press release made clear that there were two problems (a problematic fiber-optic cable and a miscalibrated oscillator), causing shifts in opposite directions, and mentioned that a re-run of the experiment would be necessary.  Still, most press articles seemed to give this lip service, and assume the correct reading of the situation was that the fiber was the main source of the problem, and that a re-run of the experiment was just pro forma.  They mostly stuck with the simplistic idea that the OPERA people found a mistake and now everything agrees nicely with Einstein.  A few, such as the New York Times, did a somewhat better job.  But they still missed key points.

So what is the real story?  

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Synopsis of the OPERA Situation

I thought I’d better try to clarify what the logical issues are regarding OPERA before things get too confusing.  [Read the previous post first.] What’s going on is sketched in the Figure below. a) In September (and confirmed in November) OPERA claimed to have found that, compared to expectations, neutrinos from CERN seemed to be arriving … Read more

About the NY Times article from 8/02/11

On Tuesday, the New York Times had an article on the Higgs particle search.  Not bad, and does quote relevant people, but just a little bit thin on content.  If you want some actual content, try my article on the hints of the Higgs particle. Also, the article falls into the common mistake of not … Read more

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